The need for magnification of a surgical or medical procedure site is widely recognized in the medical arts, and a number of devices are available for this purpose. The most common device is the loupe (or pair of loupes), which is essentially a lens mounted to an eyeglass frame. Although the loupe is relatively inexpensive and suffices for certain procedures, the magnification factor of the device is limited and the loupe is inadequate for a wide range of procedures.
Recognizing the need for increased magnification, the art turned to various types of surgical microscope configurations. One such device is a self-contained head mounted system wherein the microscope and associated components are mounted on a head harness worn by the surgeon. Reference is made, for example, to the devices described in U.S. Pat. No. 4,616,257 and the PCT application WO 03/069214. More recently, the company Life Optics Corporation having a principal place of business in Chicago, Ill., has introduced a line of head-mounted microscopes under the family name “Varioscope®” for use in surgical and dental procedures.
A drawback, however, with the head mounted systems is that the overall weight of the system is borne essentially entirely by the operator's head. This can be problematic, particularly during relatively long and intense procedures wherein any variable that adds to surgeon fatigue should be minimized. The head mounted systems may even include counterweights at the back of the head harness to offset the weight of the scope at the front of the harness. These counterweights only add to the overall weight of the device. The effort to overcome the inertia of the relatively heavy head mounted systems, and subsequent braking of the motion of the system at a desired position and angular orientation of the scope, is an unnatural exercise for the surgeon and can make the device difficult and frustrating to use. This is particularly true at higher magnification powers wherein even a slight positional overshoot of the scope may result in a total loss of the relevant viewing field and a subsequent erratic “hunt-and-seek” effort to relocate the viewing field.
Analytical microscope systems are also known wherein the scope is supported by an adjustable structure, such as an articulated, counterbalanced boom-type structure. Reference is made, for example, to the devices described in U.S. Pat. Nos. 4,344,595; 4,515,333; and 5,253,832. Seiler Instrument & Manufacturing Company of St. Louis, Mo., manufactures and markets a line of dental microscopes (Model SSI) with a binocular scope on a counterbalanced pantographic arm. The optical head is manually positioned with handles provided on the head unit, and the scope is focused either manually or by a foot controlled motorized unit. In general, these devices utilize various mechanical configurations to support the scope at a fully supported position and angular orientation. In this regard, such systems may be considered as externally stabilized systems wherein the position of the scope is manually adjusted and then maintained by the support structure independent of the position of the operator's head. In other words, orientation of the operator's line of sight (and thus the visual field) is dictated by the static position of the externally supported scope. The scope does not follow movement of the operator's head. Certain of these externally stabilized systems may utilize a power assist drive unit, such as an electrical or hydraulic motor, to position the scope and relatively heavy support structure.
An inherent drawback of the externally stabilized suspended systems is that the procedure must be stopped in order to reposition the scope, particularly if this must be done by hand with handles provided on the optical heads. Additionally, upon repositioning the scope, the overall weight of the scope and support structure results in a momentum that tends to carry the device beyond its desired position, often resulting in numerous and embarrassing attempts to correctly position the scope. The power assist devices offer some improvement in this area, but are complicated, cost prohibitive for many practitioners, and do not offer total uninhibited range and motion of the scope. They also require a high degree of spatial coordination by the operator to externally drive the optical head with a power unit to a desired orientation while looking through the scope. Again, position of the scope is not slaved to movement of the operator's head, but to external manual or power manipulation of the optical head unit.
A need therefore exists for an improved system and apparatus for supporting a surgical microscope that is lightweight, easy to use, relatively uncomplicated and affordable, and addresses drawbacks of the known systems. The present invention provides such a system.